In general, infrared radiation (IR) sensors are used in a variety of applications to detect infrared radiation and provide an electrical output that is a measure of the incident infrared radiation. One type of infrared sensor is a bolometer. A bolometer is typically formed on a substrate or wafer and includes an absorber element for absorbing infrared radiation and a transducer element in thermal contact with the absorber element that has an electrical resistance that varies with temperature. In operation, infrared radiation incident upon the bolometer is absorbed by the absorber element, and heat generated by the absorbed radiation is transferred to the transducer element. As the transducer element heats in response to the absorbed radiation, the electrical resistance of the transducer element will change in a predetermined manner. By detecting changes in the electrical resistance, a measure of the incident infrared radiation can be obtained.
In previously known bolometer infrared sensors, as depicted in FIG. 2, the absorber element 102 of the bolometer 100 is typically integrated into a support structure that is suspended above the surface of the substrate 104. In some previously known sensors, the absorber element and the support structure are formed of the same material and deposited onto the substrate at the same time. The absorber element and support structure are deposited onto a patterned sacrificial layer which is then removed beneath the support structure so that the absorber element and support structure are suspended at the same level above the substrate. Upon removal, the absorber element and support structure are suspended above the substrate by support arms 106 that have an L-shaped configuration.
While effective for suspending the absorber element and support structure above the substrate, stress in the absorber element and support structure can result in buckling and shifting of the absorber element. Buckling and shifting of the absorber can result in reduced planarity, or flatness, of the absorber and can cause a non-uniform spacing between the absorber and the substrate which can adversely impact the accuracy and consistency of the sensor. In addition, the L-shaped arms 106 reduce the fill factor of the device.